查询词典 systematic sampling

This paper utilizes FFT after undersampling to analyze the relationship between the estimation of sinusoidal parameters and corresponding actual values on the basis of bandpass sampling theorem. In addition, the errors of parameter estimation using phase difference are deduced strictly.

摘要该文从带通采样定理出发，分析了欠采样后利用FFT估得的正弦信号参数与真实值之间的关系，并对欠采样下基于相位差分法的参数估计的误差进行了严格的推导。

The scattering coefficients of a single charged sphere are deduced. And with spherical vector wave functions and addition theorem, the scattering coefficients of multiple charged and uncharged spheres are derived. The sampling method of simulating a Gaussian beam in use of MC is provided.

详细推导了单个带电球粒子的散射系数；并采用矢量波函数展开方法结合矢量波函数的加法定理导出了高斯波束入射多个带电/不带电球粒子的散射系数；提出了用MC模拟高斯波束的抽样方法。

A phase advancer has a main AC-AC frequency conversion circuit consisting of thyristors.When sampling circuit detects the zero passage signal produced in rotor current of motor,main circuit controlled with advanced microcomputer controlling technique will change the AC voltage of 380V,50HZ into compensating voltage with the same frequency as that of rotor voltage and rotor current 90°in phase lay to achieve the goal to raise the power factor of the motor.

由可控硅构成的交变频主电路，在采样电路检测到电机转子电流产生的过零信号后，经过先进的微机控制技术控制主电路，将380V、50HZ交流电压转换成转子频率相同，相位滞后转子电流90°的补偿电压，达到提高电动机功率因数的目的。

This study pays emphases on Sampling and examination of aerosol.

本实验的重点也是气溶胶的采样与检测。

Sampling and examination of aerosol is an important mean to research of atmospheric pollution.

气溶胶的采样检测是国内外研究大气污染的重要手段。

A study cased in Zhejiang Province, China, showed the fact that the three-phase sampling could produce the highest AFI area estimation precision.

用浙江省实际数据计算的结果表明：三相抽样精度明显比其他估计方法高。

Methods A total of 852 children aged from 9 to 10 years were recruited with multi-stage sampling.

方法采用多阶段随机整群抽样法抽取852名北京市城区9～10岁学生。

Air quality information-sampling is very important to manage and control air cleaner.

空气质量采集对空气清新器的管理和控制起着关键的作用。

Smoking ; air pollution ; sampling survey

吸烟；大气污染；抽样调查

Objective］ GC analytical method for butyl ether in the workplace air using sampling by charcoal tube was studied.

目的］ 研究炭管采集空气中丁醚的气相色谱分析方法。

For the head-teacher of the class said that I had seriously broken the school rules,which led me to a three-day suspend class.

为什么呢？因为我的班主任说我严重的违反了校规，于是让我停课三天。

Many of them believe that the conversion of thousands of working-class folk in England spared that nation from the mass carnage and the tyranny that came with the revolution in France.

他们之中有许多人相信，在英国数以千计的劳工阶级之悔改信主使英国免於遭受如法国大革命所造成的大屠杀和专制暴政。